Best point of reference for php is the php site - full online manuals with user contributed comments. http://php.net/manual/en/index.php

There's plenty of general online tutorials, but one that usually delivers the goods is www.w3schools.com - something for everything - HTML / CSS / SQL PHP ETC etc. Use it as a point of reference when you get stuck, or work through some of their tutorials

One BIG BIG tip. Don't try to teach yourself PHP / SQL by using or modding Dolphin, it's simply not very see more tidy code and will be harder to learn with. It is also full of bad coding habits that you do not want to pick up (sorry Boonex)

My best advice - start at the beginning (you may already be familiar with some of this)

1 - Write a HTML only site - learn the difference between content and style, understand how DIV and SPAN works an the relationship between bock level tags.
2 - Add in CSS - learn the difference between inline style and style sheets.
3 - Convert what you have done so far into a simple hard coded php site. Initially echo the content of the HTML page out to the browser, but then figure out how to create a simple template system - by reading in the HTML from an external file and then manipulating it by replacing markers within the content.
4 - Now move the content to a database and call it from the php script. Then read it into the code and apply it to your template.

Once this is mastered you should then look at HTML forms and learn how post vars work - then try creating a simple form to input data into the database. Then look at getting to grips with data manipulation / user authentication /